Method and arrangement for utilizing a psuedo-alloy composite for rapid prototyping and low-volume production tool making by thermal spray form techniques

ABSTRACT

Method and arrangement for spray forming an article. The method includes spraying a plurality of metal streams upon a low-heat resistant model and thereby forming a spray formed article. Each of the plurality of metal streams is composed of moltenized droplets, and as between the plurality of metal streams, each is composed of different constituent elements. In the spray form process, conditions of the metal streams are controlled, particularly around the time that the droplets land, to prevent adverse affects such as melting or burning the master model. The spray conditions are controlled in such a manner that the individual metal droplets forming the metal streams remain substantially segregate. The segregated state is maintained through out solidification so that the resulting spray formed article is composed at least partially of psuedo-alloy.

BACKGROUND OF INVENTION

There are many situations in which it is desired that a prototype orlow-volume production tool be made from a master model constructed fromrelatively low heat-resistant material; that is, the material out ofwhich the model is constructed either softens and/or melts at arelatively low temperature, or is combustible at comparatively lowtemperatures. Examples of such materials of construction for mastermodels that would be desirably accommodated include wax, wood, plasticand similar materials.

It is known to use zinc alone in spray forming processes on such lowheat-resistant materials, but the resulting tool is relatively softbecause of its exclusive, or near-exclusive zinc content. As a result,tools of only very limited application may be formed in such a manner.These tools are normally limited to prototype applications because theydo not possess sufficient durability to withstand even low-volumeproduction manufacturing.

Conventional thermal spray form molding has utilized metals whichrequire substantial energy input, which is typically manifest as heatenergy, to moltenize and make the metal sprayable. Because of the hightemperature of such a moltenized metal when it strikes the master model,the model has typically been required to be constructed from high heattolerant material, such as ceramic, in order to survive the spraying ofsuch molten metal thereupon. Because the original model is not typicallycast directly in ceramic, multiple steps are required to finallyestablish a ceramic master model from one that has been constructed, forinstance, by rapid prototyping methods such as stereo lithography, orwhich are constructed out of other types of low-heat resistant materialssuch as wood, wax and plastic laminate.

Because of the expense and delay associated with the usual multi-stepprocess required to establish the ceramic master model, it is highlydesirable to be able to perform spray form techniques directly upon thesurface of an original model constructed from such rapid prototypingmethods and low-heat resistant materials.

SUMMARY OF INVENTION

In at least one embodiment, the present invention takes the form of amethod for spray forming an article, such as a low-volume stamping tool.The method includes spraying a plurality of metal streams upon alow-heat resistant model and thereby forming a spray formed article.Each of the plurality of metal streams is composed of moltenizeddroplets, and as between the plurality of metal streams, each iscomposed of different constituent elements. According to the invention,conditions of the metal streams are controlled, particularly around thetime that the droplets first land, to assure that excessive heat energycontained therein is for all practical purposes, dissipated essentiallyimmediately upon contact. In this way, if there is heat imposed on themodel from the sprayed metal, it is sufficiently transitory that evenlow-heat resistant materials remain unaffected. The spray conditions arecontrolled in such a manner that the individual metal droplets formingthe metal streams remain substantially segregate; that is to say,touching one another, but without intermixing across droplet surfaceboundaries. The droplets are held together based on mechanical adhesionthat occurs when the semi-molten droplets come into contact with oneanother.

The segregated state is maintained through out solidification so thatthe resulting spray formed article is composed at least partially ofpsuedo-alloy; that is, commingled droplets of different elementalmetals, but without intermixing into true alloys. The article may alsobe considered a psuedo-alloy based on a more global perspective; thatis, the individual droplets may not be highly commingled, but differentelemental deposits that are established in the spraying process areintermingled.

In another aspect, the invention includes the control of the relativeproportions utilized of each of the metal streams that are differentlycomposed on an elemental basis in a manner that institutes prescribedperformance characteristics in the resulting spray formed article. Inthis way the qualities of the finished spray formed product can bemanipulated to assure that the article is suitable for its intended use;as an example, as a spray formed stamping tool manufactured for use inlow-volume production processes.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described in greater detail in the followingway of example only and with reference to the attached drawings, inwhich:

FIG. 1 a schematic representation of a spray form arrangement configuredaccording to an embodiment of the present invention.

FIGS. 2A-2D illustrate depositional outcomes produced when a pluralityof arc guns are aimed for adjacent, but spaced-apart depositionalpatterns according to the teachings of the present invention.

FIGS. 3A-3D illustrate depositional outcomes produced when a pluralityof arc guns are aimed for segregated, but touching depositional patternsaccording to the teachings of the present invention.

FIGS. 4A-4D illustrate depositional outcomes produced when a pluralityof arc guns are aimed for overlapping depositional patterns according tothe teachings of the present invention.

FIGS. 5A-5D illustrate depositional outcomes produced when a pluralityof arc guns are aimed for substantially commingled depositional patternsaccording to the teachings of the present invention.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale, somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as abasis for the claims and as a representative basis for teaching oneskilled in the art to variously employ the present invention.

As described herein, and as shown in the accompanying drawings, a commonmethod for establishing thermal spray formed bodies utilizes two-wirearc gun technology. In such a gun 13, two metallic wires 28,28 or 31,31are fed therethrough and sufficiently electrified so that an electricarc is established between the wires, one each acting as an anode 19 andcathode 22. The arc produced is of sufficient power to input enough heatenergy to cause both wires 28,28 or 31,31 to be melted and becomemolten. Using air jets 16, the moltenized wire 28,31 is propelled instreams toward a target.

By conventional arrangement, each of the two wires 28,28 or 31,31 of thearc gun 13 are fed by a pair of rotating wheels that are commonlygeared. As a result, the two wires 28,28 or 31,31 are fed atsubstantially the same rate through the arc. This makes it difficult, ifnot impossible, to feed two wires 28,28 or 31,31 in the same gun 13 thathave substantially different physical properties, especially withrespect to melting point. For instance, if one wire requiressubstantially more heat-energy to become molten than does the other, thewire with the higher heat requirement would necessarily have to be fedmore slowly through the arc. Conversely, the wire of lower heatrequirement for moltenization is often referred to as having a “quickerburn rate” than the higher melting point wire. The quicker burning wirewith the lower melting point can actually burn backwards away from thearc toward the gun if the feed speed is geared for the slower burning,higher melting point wire. As a result, undesirable sputtering andmisdirection of the molten metal can occur.

In order to take advantage of superior qualities that are produced in atool resulting from thermal spray form techniques that utilize wires ofdifferent composition, the present invention employs a plurality of guns13. That is to say, at least two guns 13 are utilized, but in apreferred embodiment, four guns 13 are utilized.

As background, the wire(s) 28 and 31 utilized in the present inventionare supplied as off-the-shelf products. In addition to manufacturingwire that is comprised of predominantly one element as is utilized in atleast one aspect of the present invention, these same suppliers normallyalso provide alloy wire, such as a zinc/copper combination that iseffectively wire composed of the alloy brass. The composition of thistype of alloy-wire is necessarily limited by the acceptable proportionsfor forming the alloy brass. The present invention, however, utilizesdifferent metal-type wire 28 and 31 in each of the different guns 13,but the wires 28,28 or 31,31 in any given gun 13 are alike and oftenpredominantly mono-elemental. As an example, in a two gun 13 arrangementas illustrated in FIG. 1, zinc wire 28 might be utilized in one gun 13while copper or steel wire 31 is utilize in the other. Since an actualalloy is not prescribed to be formed according to the present invention,a much wider range of compositional combinations, as well as a widerarray of possible resulting characteristics in the spray formed body areachievable. The guns 13 are shown to be at different depositional stagesor volumetric rates; that is, more moltenized wire 31 has been depositedon the right than has been deposited on the left of the different typemoltenized wire 28. It is contemplated that the depositionalcharacteristics of simultaneously sprayed streams may varyvolumetrically; they may also be volumetrically balanced as illustratedat least in FIG. 2A.

In one embodiment of the present invention, during the spraying processthe two guns 13 are not directed at the same location, but are insteaddirected at points adjacent to one another as is shown in FIGS. 2A-2D.Resultingly, the two metals, exemplarily zinc and copper, can beconfigured to establish what amounts to predominantly separate stripes54 of the respective metals as the guns 13 traverse the surfaces 43 uponwhich the molten metals are being deposited. Among others, it is forthis reason that the resulting tool is described as being composed of apseudo-alloy composite, and not an actual alloy such as brass as wouldbe the case when taking zinc and copper as the examples.

By maintaining the metals in their segregated state, a broader range ofqualities can be obtained therefrom than when using a true alloy.Referring again to the example of brass, that alloy can only beestablished within particular percentage ranges of zinc with respectcopper. When maintained separately, the percentage composition of theresulting spray formed body may be composed of any combination rangingfrom predominantly zinc and little copper to predominantly copper andlittle zinc. In this way, the desired qualities of the two metals can beadvantageously exploited to the fullest extent. Regarding comparablespray formed compositions, those desired qualities can include bettertensile strength, better thermal conductivity, better hardness andbetter dimensional stability. At least in part, this better dimensionalstability is accomplished by controlling stress that is induced in theresulting spray formed body. The goal of stress control can also beaccomplished through the manipulation of the percentages of each of thedifferent metal types utilized to establish the psuedo-alloy orcomposite spray formed body.

It should be appreciated that zinc is a preferred metal to be utilizedin spray form techniques that are to be carried out on such master modelsubstrates as wood, wax, plastic and other materials vulnerable to thehigh temperatures associated with conventional spray form techniques.The utilization of zinc is preferred because of that element'srelatively low melting temperature. That is, if a high content of zincis utilized, then a generally lower application temperature will beenabled at the master model.

A problem, however, with spray formed bodies having a high zinccomposition is that they are relatively soft, as opposed to othersprayed metals, thereby preventing tools formed by such metals frombeing used in such applications as stamping tools for metal pieces inwhich harder materials of construction are required.

The melting point for zinc is approximately 450 degrees Celsius.Compared to other metals and alloys, however, this is a relatively lowmelting temperature. Resultingly, when the parameters at the spray gun13 are properly controlled, after being moltenized in the gun's arc, thesprayed zinc 34 may be cooled to a temperature as low as 50 degreesCelsius as it travels away from the gun and immediately upon strikingthe master model substrate 12. At this temperature, the zinc isquasi-molten because it partially solidifies in flight, but it stillreadily forms a metallic bond with surroundingly deposited metals.Interestingly, a quasi-molten metal having a temperature as low as 50degrees Celsius immediately after contact can actually be sprayed upon aperson without causing harm or discomfort, thereby permitting the personto serve as a master model.

With regard to master models 12 constructed from such low-heat resistantmaterials as wax and plastic, or those established using stereolithography, application temperatures below the 50-70 degree Celsiusrange will typically be satisfactory for conducting spray formtechniques directly thereupon. The degree of cooling of the molten metalcan be controlled by, among other parameters, adjusting the distancebetween the guns 13 and the master model 12; adjusting the type,temperature and/or volume of pressured gas supplied as the carrier forthe moltenized metal; and the applied gun arc amperage and/or voltage.Still further, auxiliary cooling may be provided in the form of acooling fan that directs a flow of ambient or cooled air upon thearticle being spray formed.

In ordered to combat the undesirable characteristics experienced whenpure zinc is utilized in spray formed bodies that are intended to beutilized for prototype or rapid tooling applications, the presentinvention strategically incorporates other metals thereby forming acomposite pseudo-alloy body. As discussed hereinabove, the establishmentof the composite is accommodated by the use of multiple guns 13 whichcan be independently controlled. The present invention appreciates theutility of incorporating steel 37 or copper 37 together with the zinc 34for obtaining a harder and stronger spray formed body or tool. Each ofthese metals, however, have substantially higher melting points thandoes zinc 34. Therefore, there is a limit to the percentage content ofthese non-zinc metals 37 that can be incorporated. The two competingparameters that must be balanced is the desire for a high content of thenon-zinc metal(s) 37 for hardness and durability in the resulting toolversus low application temperature at the master model 12 that isprimarily enabled by high zinc content.

The compositional layering enabled by spray form techniques may also beadvantageously exploited. In order to accommodate the necessarily lowtemperature required at the surface 43 of a master model substrate 12made exemplarily from wax, a high content zinc layer may be initiallysprayed upon the master model 12, with an increasingly higher non-zincmetal content being subsequently applied in the build-up layers. It iswithin these subsequent layers that the pseudo-alloy is predominantlyestablished. The layers are in fact quite thin and there can be a degreeof intermix between adjacent layers.

The present invention advantageously manipulates these spray-variablesfor increasing the hardness, strength and durability of a toolmanufactured by the instant spray form techniques, while at the sametime, minimizing internal stress within the tool body. By minimizing theinternal stress either by avoiding original inducement of stress(stress-free) or by negating/canceling internal stresses within the body(no-stress), shape-distortion in the finished article is avoided. Thiscan be especially important as between the multiple built-up layers inorder to avoid warping of the article. Minimized stress is alsodesirable in order to prevent the spray formed body from tending to pullaway from the master model substrate 12.

One way for controlling the stress in a spray formed body is to controlthe temperature at which the molten metal is first applied to the mastermodel substrate 12, and also in the subsequent layers as the body isbuilt up. The general goal is to minimize the differential between thetemperature at which the molten metal 34,37 strikes the body and thetemperature to which it ultimately cools. By minimizing thisdifferential, there is a minimized degree of contraction due to cooling.

In practice, the spray guns 13 may be moved back and forth across thearticle being spray formed in substantially straight lines so that“stripes” of the respective sprayed metals 34,37 are established. Insome instances, commingled bands of pseudo-alloy are establishedtherebetween. After a layer or one series of stripes has been completed,the master model substrate 12 may be indexed to a transverse position,exemplarily to approximately 90 degrees from which a perpendicularstripe pattern is established in the subsequent application or layer. Byestablishing such lattice configurations between the layers, at leastsome of the stress that is induced is compensated for by the opposedpatterns and fosters the desired no-stress characteristics in theresulting spray formed body.

The internal stresses of the established spray formed article are alsocontrolled by varying the relative volumetric applications of thedifferent metals 34,37 as exemplarily shown in FIG. 1. For instance,some metals will create contractive forces within the finished productas a result of cooling, while others will experience expansion due totransformations upon cooling and impose compactive effects within thebody. By purposeful manipulation, the relative quantities among theseveral metals 34,37 being applied from the different guns 13 can beadjusted so that as close to zero stress results in the finished articleas possible. Additionally, this minimization of stress insures that thespray formed article does not pull away from the master model 12 duringthe cooling process.

Through the course of experimentation, preferred ranges for both droplet40 landing temperature and elemental composition of a finished articlehave been discovered. In trials, pseudo-alloys have been created usingzinc 34 and copper 37, as well as zinc 34 and steel 37. With respect toeach combination, a target temperature of 50 degrees Celsius has beenidentified, with an acceptable range being defined thereabout from 32degrees Celsius to 60 degrees Celsius. For zinc and copper (Zn/Cu) andzinc and steel (Zn/Fe) combinations, a particularly advantageous rangeof constituent composition percentages, measured on a by weight basis,has been identified as ranging between 60/40 and 54/46. Thesecompositions have rendered hardness values in the range of 60 to 68 forthe zinc and copper combination and 85 to 95 for the zinc and steelcombination. For comparison purposes, it should be appreciated that zincalone would have a hardness value of 46 to 52 on the utilized scale forthis same application temperature range. In the present example, thesteel utilized in the zinc and steel combination is an off-the-shelfproduct that contains 0.8 carbon steel.

Regarding the goals of spray form techniques according to the presentinvention, there are several areas of suitable utilization. One group isprototype stamping tools, low-volume production stamping tools andcertain mass production stamping tools. The resulting tools can,however, be relatively soft as compared to tools constructed from truealloys and are typically not suited for long-range continuous massproduction metal stamping processes. They are, however, especiallysuited for utilization in plastic blow molding processes, plasticinjection molding processes, and as serving as lay-up tools utilized inaircraft construction. In these latter cases, sufficient hardness iseasily established using the pseudo-alloys of zinc described hereinhaving steel, copper and/or similar elements added thereto.

As intimated hereinabove, in at least one embodiment the presentinvention takes the form of a method for spray forming an article. Themethod includes spraying a plurality of metal streams 25 upon a low-heatresistant model 12 and thereby forming a spray formed article. Each ofthe plurality of metal streams 25 is composed of moltenized droplets 40,and as between the plurality of metal streams 25, each is composed ofdifferent constituent elements. In the spray form process, conditions ofthe metal streams 25 are controlled, and particularly around the timethat the droplets 40 strike first, the exterior receiving surface 43 ofthe model 12, and then the exposed outside surfaces 43 of the sequentialmetal layers as they are built-up in the spray form process. The sprayconditions are controlled in such a manner that the individual metaldroplets 40 forming the metal streams 25 remain substantially segregate;that is to say, touching one another, but without intermixing acrossdroplet surface boundaries. The segregated state is maintained throughout solidification so that the resulting spray formed article iscomposed at least partially of psuedo-alloy; that is, commingleddroplets 40 of different elemental metals, but without intermixing intotrue allows. In this manner, the droplets 40 are held together based onmechanically adhesion occurring when the semi-molten droplets 40 comeinto contact with one another. In another aspect, the invention includesthe control of the relative proportions utilized of each of theplurality of metal streams 25 in a manner that institutes prescribedperformance characteristics in the spray formed article thereby assuringthat the spray formed article is suitable for intended use.

In practice, feed-wire 28 or 31 is fed respectively to arc guns 13 thatestablish the plurality of metal streams 25. The feed-wires 28,31 areselected so that one pair of wire strands 28 going to one gun 13 iscomposed predominantly of zinc metal and another pair of wire strands 31going to the other gun 13 are composed predominantly of non-zinc metal.In a preferred embodiment, the predominantly non-zinc metal feed-wire 31has sufficient amounts of steel, copper or other suitable metal toestablish a wear resistant mold that can be used in such manufacturingprocesses as blow molding and/or injection molding. Still further, alow-volume stamping tool may be similarly spray formed.

The relative proportions may be manipulated and varied between theplurality of metal streams 25 with regard to elemental constituentmake-up during the spraying process. In this way, the user can tailorthe characteristics of the spray formed article for custom applications.

Varying the elemental make-up can also be used to establish a no-stressspray formed article through manipulating the relative proportions ofthe plurality of metal streams 25 to cancel out any induced stress.Similarly, a stress-free spray formed article may be formed throughcontrol of the relative proportions of the different constituentelements.

In one practice according to the present invention which is illustratedin FIGS. 2A-2D, each of the plurality of metal streams 25 is aimed atdifferent, but adjacent locations on the spray formed article. In such aspaced configuration 50, these different, but adjacent locations on thespray formed article are spaced sufficiently far apart that a gap-space52 is maintained between simultaneously sprayed metal streams 34,37.Throughout the process, each of the plurality of metal streams 25 issprayed across the spray formed article so that discrete metal stripes54 are formed on the exposed receiving surfaces 43. These surfaces 43include not only the exterior surface 43 of the master model 12, butalso the exposed surface 43 of each subsequent layer of spray formedmetal that is applied thereto. The metal stripes 54 are spaced apart sothat parallel and discrete metal stripes 54 with essentially no overlaptherebetween are established across the spray formed article. Asindicated above, the orientation of the model 12 may be altered prior toa subsequent layer's application, or the guns 13 may be manipulated in across-wise direction to the previous. In either event, the parallel anddiscrete metal stripes 54 of sequential layers are applied in a latticeconfiguration 56 for minimizing stress-induced shape distortion in thefinished spray formed article. The angle at which the latticeconfiguration is established may vary, therefore, within an acceptablerange, the cross-wise metal stripes may be longitudinally transverselyoriented as shown in FIG. 2C in which a transverse lattice configuration58 is established. In one particularly preferred embodiment, theorientation of the crossing metal stripes is perpendicularly oriented asshown in FIG. 2D thereby establishing a perpendicular latticeconfiguration 59.

In an exemplary embodiment, the non-zinc feed-wire 31 is comprised ofsufficient amounts of steel to establish the spray formed article as alow-volume stamping tool. The wire strands 31 are chosen so that it hassufficient amounts of the non-zinc metal, exemplarily steel, toestablish a spray formed article capable of being used as a low-volumestamping tool.

As indicated above, but for clarity within the context of the teachingsof the method(s) of the present invention, application conditionsregarding the plurality of metal streams 25 are controlled so thatimmediately upon striking the exposed receiving surfaces 43, the metaldroplets 40 have a temperature ranging from approximately 32 degrees to60 degrees Celsius thereby avoiding softening and combusting a low-heatresistant model 12. A preferred temperature has been found to beapproximately 50 degrees Celsius, which avoids softening, and/orcombusting a low-heat resistant model 12.

In one configuration that is illustrated in FIGS. 3A-3D, the aiming ofthe metal streams 25 causes a segregation interface 62 to be establishedbetween the simultaneously sprayed metal streams 25. There isessentially no overlap between the simultaneously sprayed plurality ofmetal streams 25. As the metal is sprayed across the spray formedarticle, segregated, but interfacing metal stripes 64 are formed. Aninterfaced relationship 60 is maintained between the metal stripes 64 sothat the parallel metal stripes 64 touch one another, but there isessentially no overlap between the metal stripes 64. As in the spacedapart embodiment, the parallel metal stripes 64 may be arranged into alattice configuration 66 that may be transverse 68 or perpendicular 69for minimizing stress-induced shape distortion in the finished sprayformed article.

In an alternative execution of the method of the present inventiondemonstrated in FIGS. 4A-4D, an overlapping interface 72 may beestablished between simultaneously sprayed metal streams therebyestablishing an interposed psuedo-alloy zone. During the spray process,an overlapped inter-relationship or configuration 70 is maintainedbetween overlapping metal stripes 74 so that the parallel metal stripes74 overlap one another thereby establishing an interposed psuedo-alloystripe-zone 72. As in the other embodiments, the overlapping metalstripes 74 may also be arranged into a lattice configuration 76 that maybe transverse 78 or perpendicular 79 for minimizing stress-induced shapedistortion in the finished spray formed article.

FIGS. 5A-5D show yet another possible execution of the present inventionin which a substantially commingled configuration 80 is establishedhaving a commingled interface 82 formed by commingled metal stripes 84.In this configuration, the target location for each of the spray streams25 is substantially identical, but possibly with a slight offset. Aswith the other embodiments, the commingled metal stripes 84 may also bearranged into a lattice configuration 86 that may be transverse 88 orperpendicular 89 for minimizing stress-induced shape distortion in thefinished spray formed article.

A method for establishing a dimensionally stable spray formed articlehas been variously described. These and other variations, which will beappreciated by those skilled in the art, are within the intended scopeof this invention as claimed below. As previously stated, detailedembodiments of the present invention are disclosed herein; however, itis to be understood that the disclosed embodiments are merely exemplaryof the invention that may be embodied in various forms.

What is claimed is:
 1. A method for spray forming an article, saidmethod comprising: spraying a plurality of metal streams upon a low-heatresistant model and thereby forming a spray formed article, each of saidplurality of metal streams being composed of moltenized droplets, and asbetween the plurality of metal streams, each is composed of differentconstituent elements; controlling application conditions of saidplurality of metal streams upon exposed receiving surfaces during thespraying process so that individual metal droplets of said plurality ofmetal streams remain substantially segregate through out solidificationand thereby establish said spray formed article composed at leastpartially of a psuedo-alloy; and controlling relative proportionsbetween said plurality of metal streams composed of differentconstituent elements by varying said relative proportions during thespraying process and thereby customizing characteristics of said sprayarticle.
 2. The method as recited in claim 1, further comprising:supplying feed-wire to arc guns that establish said plurality of metalstreams; and selecting said feed-wire so that a strand of wire iscomposed predominantly of zinc metal and another strand of wire iscomposed predominantly of non-zinc metal.
 3. The method as recited inclaim 2, further comprising: selecting said predominantly non-zinc metalfeed-wire to comprise sufficient amounts of steel to establish saidspray formed article as a wear resistant molding form.
 4. The method asrecited in claim 2, further comprising: selecting said predominantlynon-zinc metal feed-wire to comprise sufficient amounts of copper toestablish said spray formed article as a low-volume stamping tool. 5.The method as recited in claim 1, further comprising: supplyingfeed-wire to arc guns that establish said plurality of metal streams;selecting said feed-wire so that a strand of wire is composedpredominantly of zinc metal and another strand of wire is composedpredominantly of non-zinc metal; and controlling wire feed conditions sothat said spray formed article, on a by-weight basis, comprises between54 and 60 percent zinc metal and between 40 and 46 percent non-zincmetal, respectively.
 6. The method as recited in claim 1, furthercomprising: establishing a no-stress spray formed article bymanipulating said variation of said relative proportions between saidplurality of metal streams composed of different constituent elementsduring the spraying process.
 7. The method as recited in claim 1,further comprising: forming a stress-free spray formed article bymanipulating said variation of said relative proportions between saidplurality of metal streams composed of different constituent elementsduring the spraying process.
 8. The method as recited in claim 1,further comprising: aiming each of said plurality of metal streams atdifferent, but adjacent locations on said spray formed article; andspacing said different, but adjacent locations on said spray formedarticle sufficiently far apart that a gap-space is maintained betweensimultaneously sprayed metal streams.
 9. The method as recited in claim8, further comprising: spraying each of said plurality of metal streamsacross said spray formed article so that discrete metal stripes areformed on the exposed receiving surfaces; and spacing said metal stripesapart so that parallel and discrete metal stripes with essentially nooverlap therebetween are established across said spray formed article.10. The method as recited in claim 9, further comprising: arranging saidparallel and discrete metal stripes into a lattice configuration forminimizing stress-induced shape distortion in the finished spray formedarticle.
 11. The method as recited in claim 10, further comprising:configuring said lattice configuration so that crossing metal stripesare longitudinally transversely oriented.
 12. The method as recited inclaim 11, further comprising: configuring said longitudinallytransversely oriented crossing metal stripes to be perpendicularlyoriented.
 13. The method as recited in claim 1, further comprising:supplying feed-wire to arc guns that establish said plurality of metalstreams; and selecting said feed-wire so that a strand of wire iscomposed predominantly of zinc metal and another strand of wire iscomprised of sufficient amounts of steel to establish said spray formedarticle as a low-volume stamping tool.
 14. The method as recited inclaim 1, further comprising: supplying feed-wire to arc guns thatestablish said plurality of metal streams, each of said plurality ofmetal streams being composed of different constituent elements;selecting said feed-wire so that a strand of wire is composedpredominantly of zinc metal and another strand of wire is comprised ofnon-zinc metal; and choosing said strand of wire that comprises non-zincmetal to have sufficient amounts of said non-zinc metal to establishsaid spray formed article as a low-volume stamping tool.
 15. The methodas recited in claim 1, further comprising: controlling applicationconditions of said plurality of metal streams so that immediately uponstriking said exposed receiving surfaces, said metal droplets have atemperature ranging from approximately 32 degrees to 60 degrees Celsiusthereby avoiding softening and combusting a low-heat resistant model.16. The method as recited in claim 1, further comprising: controllingapplication conditions of said plurality of metal streams so thatimmediately upon striking said exposed receiving surfaces, said metaldroplets have a temperature of approximately 50 degrees Celsius therebyavoiding softening and combusting a low-heat resistant model.
 17. Themethod as recited in claim 1, further comprising: aiming each of saidplurality of metal streams at different, but adjacent locations on saidspray formed article; and spacing said different, but adjacent locationson said spray formed article so that a segregation interface isestablished between simultaneously sprayed plurality of metal streams,but there is essentially no overlap between said simultaneously sprayedplurality of metal streams.
 18. The method as recited in claim 17,further comprising: spraying each of said plurality of metal streamsacross said spray formed article so that segregated, but interfacingmetal stripes are formed on the exposed receiving surfaces; andmaintaining an interfacing relationship between said metal stripes sothat parallel metal stripes touch one another, but there is essentiallyno overlap between said metal stripes.
 19. The method as recited inclaim 18, further comprising: arranging said parallel metal stripes intoa lattice configuration for minimizing stress-induced shape distortionin the finished spray formed article.
 20. The method as recited in claim1, further comprising: aiming each of said plurality of metal streams atdifferent, but adjacent locations on said spray formed article; andspacing said different, but adjacent locations on said spray formedarticle so that an overlapping interface is established betweensimultaneously sprayed metal streams thereby establishing an interposedpsuedo-alloy zone.
 21. The method as recited in claim 20, furthercomprising: spraying each of said plurality of metal streams across saidspray formed article so that overlapping metal stripes are formed on theexposed receiving surfaces of said spray formed article; and maintainingan overlapped inter-relationship between said metal stripes so thatparallel metal stripes overlap one another thereby establishing aninterposed psuedo-alloy stripe-zone.
 22. The method as recited in claim21, further comprising: arranging said parallel metal stripes into alattice configuration for minimizing stress-induced shape distortion inthe finished spray formed article.